Preheat oven to 350F. Butter one tall (2 – 2.5 inch deep) 9-inch cake pan.
In the bowl of a stand mixer fitted with a paddle attachment, cream butter until smooth. Add sugar and salt & cream until light and fluffy.
Slowly pour room temperature caramel syrup into bowl. Scrape down bowl and increase speed. Add eggs/vanilla extract a little at a time, mixing well after each addition. Scrape down bowl again, beat mixture until light and uniform.
Sift flour and baking powder. Turn mixer to lowest speed, and add one third of the dry ingredients. When incorporated, add half of the milk, a little at a time. Add another third of the dry ingredients, then the other half of the milk and finish with the dry ingredients.
Take off mixer and by hand, use a spatula to do a few last folds, making sure batter is uniform. Turn batter into prepared cake pan. Place cake pan on cookie sheet or 1/2 sheet pan. Set first timer for 30 minutes, rotate pan and set timer for another 15-20 minutes. Bake until sides pull away from the pan and skewer inserted in middle comes out clean. Cool cake completely before icing it. Cake will keep for three days outside of the refrigerator.

In a small stainless steel saucepan, with tall sides, mix water and sugar until mixture feels like wet sand. Brush down any stray sugar crystals with wet pastry brush. Turn on heat to highest flame. Cook until dark amber.
When color is achieved, very carefully pour in one cup of water. Caramel will jump and sputter about! It is very dangerous, so have long sleeves on and be prepared to step back.
Whisk over medium heat until it has reduced slightly and feels sticky between two fingers. {Obviously wait for it to cool on a spoon before touching it.}

Cook butter until brown. Pour through a fine meshed sieve into a heatproof bowl, set aside to cool.
Pour cooled brown butter into mixer bowl. In a stand mixer fitted with a paddle or whisk attachment, add confectioner's sugar a little at a time. When mixture looks too chunky to take any more, add a bit of cream and caramel syrup. Repeat until mixture looks smooth and all confectioner's sugar has been incorporated.

Combine all the ingredients in a heavy saucepan and bring them to a boil. Monitor the temperature with a candy thermometer and bring the mixture to 300F and the color is slightly golden. While the caramel is reaching its desired temperature, take a sheet of parchment paper and crinkle it between your hands then flatten it out a bit. This will help with the forming of the bubbles. When the caramel is ready, slowly pour it over the parchment paper. You can lift the paper carefully to spread it around the surface if needed but watch out! I do this over a large sheet pan so all is required for clean up is hot water. Let cool completely before breaking into shards.

Because it is only one layer, decorating this cake is very simple. Feel free to add a second layer if you want.